Many compounds are disclosed that inhibit Rho GTPases that are useful for inhibiting hyperprofilerative and neoplastic diseases. Specifically, the compounds inhibit the GTPases Rac and Cdc42 that are overactive or overexpressed in signaling pathways in cancer and metastasis. Methods for treatment of cancer and hyperproliferative diseases are disclosed.
The Rho GTPases Rac (Ras-related C3 botulinum toxin substrate) and Cdc42 (cell division control protein 42 homolog) regulate cell functions governing cancer malignancy, including cell polarity, migration, and cell cycle progression. The Rho family of GTPases in humans consists of 20 different members, and aberrant behavior in their regulatory activity has been implicated in cancer and other diseases. More than 70 Guanine nucleotide Exchange Factors (GEFs) are known, which specifically activate one or more of the GTPases. In turn, the activated GTPases can specifically interact with over 60 downstream effectors. Dysregulation of one or more cellular processes can lead to release of malignant cells from their original locations, which subsequently can establish themselves in pre-metastatic niches in, for example, bone or lungs. It has been found that members of the Rho GTPase family, including Rac, Cdc42 and Rho, play key signaling roles in these processes.
Rho GTPases regulate migration and invasion, cytoskeletal organization, transcriptional regulation, cell cycle progression, apoptosis, vesicle trafficking, and cell-to-cell and cell-to-extracellular matrix adhesions. The Rho GTPases Rac and Cdc42 are potent inducers of actin polymerization and extension of actin structures at the leading edge of motile cells. In addition, Cdc42 plays a critical role in cell polarity, and thus, promotes directed and persistent migration.
Studies have implicated hyperactive Rac and Cdc42 with increased cancer cell survival, proliferation, and invasion, as well in Ras and other oncogene-mediated transformation. Furthermore, oncogenic cell surface receptors, such as tyrosine kinase, cytokine, and G protein coupled receptors, activate Rac and Cdc42 via regulation of their upstream effector GEFs. Accordingly, Rac and Cdc42 proteins are generally not mutated in cancer but rather overexpressed or hyperactivated. Even though ˜9% of melanomas contain an activating Rac(P29S) mutation, and the hyperactive splice variant Rac1b is overexpressed in some cancers, a majority of the Rac and Cdc42 in human cancer are activated due to upregulated GEFs.
Of the direct downstream effectors of Rac and Cdc42, p21-activated kinases (PAK) are overexpressed in a number of cancers and contribute to cancer transformation and progression by regulating key cellular functions, including cytoskeletal organization, cell migration, adhesion, growth, and development. Therefore, a number of PAK inhibitors have been developed as anti-cancer therapeutics. However, these have been limited by specificity, bioavailability, and toxicity, and have yet to successfully complete clinical trials.
In cancer patients, the ability of tumor cells to spread from primary tumors (and metastatic tumors) is the major cause of death. In the case that breast cancer is detected and treated prior to metastasis, the patient has higher probability of being cured of their disease. To successfully invade a secondary site, a cancer cell must complete a series of steps including separation from primary tumor (intravasation), invasion through surrounding tissues and basement membranes, entry and survival in the circulation, and arrest in a distant target organ (extravasation). During cancer cell invasion, tumor cell migration through tissues, frequently requires the degradation of the extracellular matrix (ECM) and several proteins play a key role in this process. Moreover, invadopodia are actin-rich protrusive structures with associated matrix degradation activity and are believed to be important for tumor cells to penetrate the basement membrane of epithelia and blood vessels. The small GTPase Rac1, a member of the Ras superfamily of GTPases has been implicated in regulating migration and invasion of breast cancer cells. Rac1 is activated by GTP/GDP exchange factors (GEF) that are regulated via a myriad of cell surface receptors. Therefore, therapeutic strategies targeting the binding of Rac1 to GEFs are a rational means to inhibit migration of cancer cells.
The carbazole skeleton contained in many synthetic and natural compounds is the key structural motif of many biological activities that are related to this type of molecules.
Many carbazole derivatives are well known for their various pharmacological activities such as antioxidant, anti-inflammatories, antibacterial, antitumor, anticonvulsant, antipsychotics, antidiabetics, and larvicidal properties. The cytotoxic activity of carbazole alkaloids has been related to their polycyclic, planar and aromatic structure. Some carbazole derivatives have been evaluated for their anti-tumor potential against several human tumor cell lines. The carbazole sulfonamide IG-105 is an antimitotic agent that inhibit microtubule assembly through specific interactions within tubulin structure. Modeling studies suggest that the dimethoxypyridine moiety and the carbazole group forms interactions with the hydrophobic pocket of tubulin, and that the sulfonamino group and the N atom of the carbazole forms hydrogen bonds. The HYL-6d derivative inhibits angiogenic proliferation and migration in HUVEC cells under pathological angiogenic conditions, which is critical in breast cancer progression and metastasis formation. The MHY407 is an epoxypropoxy carbazole derivative that effectively causes DNA damage by C-PARP production, topoisomerase II inhibition and cell cycle arrest at S phase by regulating cyclin D1, pRb, and p21 levels.
EHop-016 has recently been developed and inhibits metastatic cancer cell viability at concentrations of >5 μM. Results showed that EHop-016 inhibits Rac1-Vav2 interaction with IC50=1 μM, Rac1 downstream effector PAK1 by −60% at 2 μM, lamellipodia formation, and cell migration. EHop-016 and other compounds are described in PCT International Patent Application No. PCT/US2017/029921 (filed Apr. 27, 2017), which is herein incorporated by reference in its entirety.
There is a need for new therapeutic agents for the treatment of cancer and other hyperproliferative diseases. The Rac and Cdc42 GTPases are important cellular mediators that are hyperactive or overexpressed in metastatic tumors. Design of novel inhibitors of the activities of Rac and/or Cdc42 with improved activity, pharmacochemical profile and reduced toxicity is desirable.